Nowadays, thermographic cameras/thermal imagers are becoming more rugged, user-friendly, and affordable. Thus, infrared thermal imaging/infrared thermography has been widely exploited in various industrial applications, particularly in fault detection and predictive maintenance. Not only instant thermal imaging of equipment may be inspected to identify any unexpected hot spots or cold spots, but also potential component failures may be instantly identified, thereby minimizing associated losses in downtime, power outage, fires and catastrophic failures. In addition, the thermography has been applied more and more intensively for monitoring various types of electrical/electronic equipment, e.g., transformers, capacitor banks, overhead power lines, power supplies, substations, switchgears, and etc. The infrared thermography is becoming one of the most effective technologies for diagnosing conditions of a machine, which allows instant detection of anomalies with precise, non-invasive temperature measurement.
Here, FIG. 4 will be referenced to briefly introduce the working principle of an infrared thermal imager as prior art. Infrared thermography is a science of detecting and measuring radiation with a photoelectric device and establishing an interrelation between radiation and surface temperature. Radiation refers to transfer of heat occurring when radiation energy (electromagnetic wave) moves without a direct conductive medium. The working principle of a modern infrared thermal imager is detecting and measuring radiation with a photoelectric device and establishing an interrelation between radiation and surface temperature. All objects with a temperature above the absolute zero (−273° C.) will emit infrared radiation. With an infrared detector and an optical imaging object lens, the infrared thermal imager accepts the infrared radiation energy of a measured object, a distribution pattern of which infrared radiation energy is reflected onto a photosensitive element of the infrared detector, thereby obtaining an infrared thermogram corresponding to a heat distribution field on the surface of the object. Generally speaking, the infrared thermal imager transforms invisible infrared energy emitted by the object to a visible thermal image. Different colors on the thermal image represent different temperatures of the measured object. By checking the thermal image, the overall temperature distribution condition of the measured object may be observed, and heating of the measured object may be studied for determining subsequent work.
However, due to limitations of the state of the art, even in a very small electrical equipment room, a plurality of thermal imaging cameras are needed for monitoring machine conditions. Particularly for an oil filled transformer, thermal imaging of high- and low-voltage external bushing connections, cooling tubes, and cooling fans and pumps, as well as the surface of the transformer should be obtained to monitor any specific type of fault that may occur within the transformer. In this case, a plurality of thermal imaging cameras are needed to monitor different parts of the machine from different angles.
However, when the measured machine is in a compact environment, there is usually no extra space for installing thermal imaging cameras for monitoring the rear of the machine. In addition, a handheld thermal imager may also be used for thermal imaging of different parts of equipment in a compact environment. However, manpower is required to use the handheld thermal imager; besides, some parts of the machine are possibly inaccessible for thermal imaging. Further, a thermal image is usually obtained in a two-dimensional manner, which makes it very difficult to identify positions of anomalies of the machine.